1. Field of the Invention
The present invention relates to a broadband internal antenna, more specifically to a broadband internal antenna combined with a monopole antenna and a loop antenna.
2. Background Art
Today's rapid development of analog and digital communication technologies has internationally made it possible to execute various mobile community type services such as a cellular type, a personal communication system (PCS) type, a global system for mobile communication (GSM) type, a personal handy system (PHS) type and an iridium type using a satellite. In Korean, the cellular type, the PCS type and a CT-2 have been in service. In addition, a digital cordless system (DCS) type, a universal mobile telecommunications system (UMTS) type, a WiBro type and a wireless LAN (WLAN) type are in service or in preparation.
Also, the software defined radio (SDR) technology which is the next generation technology capable of suggesting the solution for system integration of the times of multi-standards, multi-bands (or broad-bands) and multi-services has globally been studied and developed. The SDR technology can process signals having from a baseband to a radio frequency (RF)/intermediate frequency (IF) band by using the elements capable of re-constitution such as high-speed digital signal processing and a field programmable gate array (FPGA). The SDR technology, which makes ceaseless communication by downloading software having the object-oriented structure to a single terminal hardware platform having the open structure in order to construct the system that is flexibly applicable to various wireless mobile communication environments, is a new system that can simultaneously provide multi-standard and multi-processing frequencies, unifying various actual communication systems in the current mobile communication market, and a variety of mobile communication services.
In particular, in the U.S., the SDR technology started from the necessity of a single system capable of making continuous communications no matter when and no matter where the military operations are executed. The traditionally-used communication equipment, which makes communication by using military communication infrastructure, is unable to receive an operation execution command in an area beyond the service region or through a damaged military network. Accordingly, it is necessary to develop the system that can make the continuous communication and is flexibly applicable to the change of the communication technology in the army. In 1995, the U.S. Department of Defense started and succeeded in the SPEAKeasy, which is the project for developing the system that can modify the service standard and execute the independent operation of hardware by changing application programs based on a hardware platform performing the common functions. This leaded to the increased investment in developing the SDR system and the start of the JTRS project for defining the object-orient based structure.
Similarly, in Europe, the SDR technology-related projects have proceeded in various forms since 1994. Furthermore, the today's SDR technology, which is considered as the next generation technology for economical benefits as well as the military goal, has started to arouse the interest of companies and has resulted in the worldwide studies through universities and various R&D centers. Based on this, the SDR communication system is expected to be applicable to not only base stations but also personal terminal systems. Accordingly, the multi-band (or broad-band) antennas that are suitable to use the SDR system have been studied and developed in the antenna field.
A variety of current multi-band (or broad-band) antennas such as a broadband antenna that can include all usable frequencies of various mobile communication services through the improvement of a band width, a reconfigurable antenna using the on/off of a signal such as a chip diode and an antenna using the multiple-resonance have been under development. This requires more compact broadband antenna to be suitable for the portability of the mobile communication terminal and to be used in broader frequency bands.